A. Field of the Invention
This invention relates to track mechanisms for doors, and in particular to an assembly of three track mechanisms for a light rail vehicle door.
B. Discussion of the Prior Art
The following U.S. Pat. Nos. bearing on the subject matter of this invention are known: 3,453,778; 3,462,881; 3,826,042; and 3,844,062.
These patents disclose essentially two track mechanism assemblies in which the door weight is carried, for the most part, by one of the track mechanisms. Broadly, the track mechanisms produce a so-called "compound movement" of the doors, i.e., a movement which is both parallel and transverse to the vehicle wall. This is a desirable feature of these track mechanisms. However, the means for achieving this feature are relatively complex with a high part count. A more direct path of actuation for achieving this feature would be desirable. It would also be desirable to better transfer the door weight back to the vehicle body, and to accomplish both of these desideratum without increasing the part count.